If your TV and the Denon both support HDMI control (CEC), there is a fair chance you can enable that on both and let the TV control the receiver power/volume. I have mine set that way simply because I don't have a very direct line of sight to the receiver from where I use the remote. There's a little lag on power-up and volume adjustments but not too bad.
Thanks. I will try this and see if it works.
Is there documentation about this that I can also read?
I couldn't find that. Here is a good read:
from the manual, when entering Denon for Receiver type:
Most likely code: 31360
Others to try: 32857, 33347, 32516, 31104, 32247, 32279, 32706, 32502, 32134, 34025, 31142, 31189